CN113950608B

CN113950608B - Circuit for controlling ignition of firework assembly

Info

Publication number: CN113950608B
Application number: CN202080043071.3A
Authority: CN
Inventors: 吉恩-卢克·佩罗
Original assignee: Nexter Munitions SA
Current assignee: Nexter Munitions SA
Priority date: 2019-06-21
Filing date: 2020-06-15
Publication date: 2024-03-22
Anticipated expiration: 2040-06-15
Also published as: US20220349686A1; EP3987243B1; CN113950608A; FR3097629B1; WO2020254943A1; US11629940B2; ZA202109782B; FR3097629A1; KR20220064362A; EP3987243A1; KR102643858B1; IL289080A

Abstract

The subject of the invention is a circuit (1) for controlling the ignition of an exploding foil pyrotechnic assembly (2). The circuit comprises at least one capacitor (3) which can be discharged into said pyrotechnic assembly (2) to detonate it; and a switching device (5) allowing the capacitor to discharge into the pyrotechnic assembly. The control circuit is characterized in that the capacitor (3) is connected to the pyrotechnic component by an array of at least three diodes (D1, D2, D3), wherein the at least three diodes (D1, D2, D3) are connected in series and in a direction that prevents the capacitor (3) from discharging, the sum of the reverse voltages of these diodes being greater than the maximum voltage that the capacitor (3) can provide, the switching means (5) comprising at least two field effect transistors (Q1, Q2), the gates of the at least two field effect transistors (Q1, Q2) being controllable simultaneously and being associated with the diode array (D1, D2, D3).

Description

Circuit for controlling ignition of firework assembly

Technical Field

The technical field of the invention is an ignition control circuit for controlling an exploding foil pyrotechnic assembly.

Background

Explosive foil pyrotechnic assemblies are most commonly known by the english name "slider". They comprise a fusible bridge through which a plasma is generated when an electric current is passed, the plasma projecting a thin layer of plastic or metallic material onto the explosion relay.

The fly-sheet has the advantages that the detonator can be manufactured without using explosive, and the operation safety is improved. Such components are known, for example, from patents US4788913 and US 4862803.

The ignition control circuits of these components typically include a capacitor charged by a generator, which allows for the provision of a pulsed discharge current having a high voltage (from 800 to 1450 volts) and a high current (about 500 amps).

Typically the ignition switch is a thyristor-type static component which operates in avalanche mode, allowing high currents to pass.

One of the drawbacks of thyristors is the need for a special control voltage, which means that a current transformer has to be provided, reducing the compactness of the ignition control circuit.

Furthermore, reliable implementation of the flyer requires prior destructive testing of the entire pyrotechnic train in order to determine the voltage required to properly operate the flyer with a given confidence and reliability over a given temperature range.

These tests (known as the Neyer test) are well known in the field of statistical analysis, particularly for pyrotechnic components.

For example, reference may be made to publications: "AD-Optimality-Based Sensitivity Test" -authors: barry, T Neyer, reissued on TECHNOMETRIS 02/1994, volume 36, stage 1, pages 61-70. Available on the internet, the web addresses are as follows:

http://neyersoftware.com/Papers/D-Optimal/D-Optimal.htm

performing these tests on samples of a batch of circuits may set the firing voltage to ensure the reliability required for the batch and given application.

Thus, the test classifies the complete priming sequence as: fly-sheet, capacitor, and static switch.

However, compact and inexpensive static switches, such as MOS transistors, are not destroyed in avalanche mode at voltages of up to 1350 volts, which are used for flyers. This results in insufficient current strength for the flyer to function properly and difficulty in characterizing the reliability of the complete starting chain.

Furthermore, the range of fly sheet control voltages is limited (between about 1300 and 1450 volts), while the required reliability performance may require lower ignition voltages, especially in the range of 800 to 1450 volts.

Disclosure of Invention

The object of the present invention is to provide an ignition control circuit of simple and compact construction which can operate over a wide voltage range (from 800 volts to 1450 volts) while allowing the ignition voltage to be defined by statistical testing of the sample according to the Neyer test, ensuring the required level of reliability.

The object of the present invention is therefore a circuit for controlling the ignition of an exploding foil pyrotechnic assembly, comprising at least one capacitor which can be discharged in the pyrotechnic assembly to detonate it, and a switching device ensuring the discharge of the capacitor in said pyrotechnic assembly, a control circuit, characterized in that the capacitor is connected to the pyrotechnic assembly by an array of at least three diodes in series, and in that the sum of the reverse voltages of these diodes is greater than the maximum voltage deliverable by the capacitor in the direction of preventing the discharge of the capacitor, the switching device comprising at least two field effect transistors, the gates of which can be controlled simultaneously and are associated with the array of diodes, each connected between two diodes in the array by one of the outputs, the control of the transistors resulting in a continuous short circuit of the three diodes and the ignition.

Advantageously, each diode may be associated with a resistor connected in parallel, so that the reverse voltage to which each diode is subjected may be limited and set.

According to a particular embodiment, each transistor may be connected between two diodes through a resistor, which makes it possible to limit the circulation of current in the transistor.

Advantageously, the transistor may be a MOS transistor. The invention may be implemented with other types of transistors.

Drawings

The invention may be better understood from the following description of specific embodiments, which are described with reference to the drawings,

fig. 1 shows an ignition control circuit according to the prior art;

fig. 2 shows an ignition control circuit according to an embodiment of the invention.

Detailed Description

Referring to fig. 1, a known ignition control circuit 1 comprises an exploding foil pyrotechnic assembly (or flyer) 2 capable of being detonated by discharge of a capacitor 3. The capacitor 3 is charged by a generator 4, the generator 4 being arranged between the input pins a and B. If the flyer 2 is incorporated into a projectile, charging of the capacitor 3 occurs at a given moment in the trajectory of the projectile, for example, or after the projectile is launched.

According to the Neyer test, the charging of the capacitor 3 is performed at a voltage level that ensures operation at a desired level of reliability.

The ignition control circuit 1 further comprises static switching means 5, for example a thyristor, which when controlled to be closed by the contact C will cause the capacitor 3 in the flyer 2 to discharge.

Fig. 2 shows an embodiment of an ignition control circuit 1 according to an embodiment of the invention.

Elements of the circuit that perform the same function as known circuits are designated by the same reference numerals.

It can be seen that capacitor 3 can again be charged from input pins a and B by generator 4.

The control circuit 1 comprises three diodes D1, D2 and D3 connected in series and in reverse (in a direction to prevent discharging of the capacitor). These diodes form an array connecting the flyer 2 and the capacitor 3.

The diodes D1, D2, and D3 are connected in a direction to prevent the capacitor 3 from discharging (the positive electrode (+) of the capacitor 3 is connected to the blocking electrode or positive electrode of the diode D1).

Pin B connected to the negative electrode (-) of the capacitor 3 constitutes the common electrode (0 volts) of the circuit 1.

Furthermore, the sum of the reverse voltages of these diodes is larger than the maximum voltage that can be provided by the capacitor 3.

Therefore, the capacitor 3 in the flyer 2 is not discharged.

For example, for a capacitor that reaches a maximum charge at 1450 volts, a diode with a reverse voltage of 600 volts may be employed. Thus, when the three diodes are connected in series, the overall reverse voltage of the circuit is 1800 volts and the capacitor 3 will not discharge.

It should be noted that the circuit needs to implement at least three diodes in view of the reverse voltage values of the diodes on the market and the voltage range required to detonate the flyer.

As shown in fig. 2, each diode D1, D2 or D3 is associated with a resistor (R1, R2 or R3, respectively) connected in parallel with the diode.

For the aforementioned voltage values, the values of these resistors are approximately 10 megaohms (10 mΩ). When the capacitor 3 is charged, each resistor limits the reverse voltage that each diode sees. Here, the reverse voltage of each diode is limited to 485 volts, which is lower than the reverse voltage of the diode (600 volts). Therefore, the diode cannot be shorted.

It should be noted that if one or more of these resistors R1 to R3 were omitted, the voltage across the diode without a resistor would be associated with the only reverse impedance of the diode under consideration. Since not all diodes are exactly the same, this may result in a voltage that is higher than the reverse voltage (600 volts) across the diode terminals, resulting in accidental damage. A resistor in parallel with the diodes may limit and set the reverse voltage that each diode is subjected to.

As far as diode D3 is concerned, it is noted that resistor R3 is not connected in parallel with diode D3 alone, but with the circuit of diode D3, wherein diode D3 is connected in series with flyer 2. This has no practical effect, since the resistance of the flyer 2 is negligible.

According to the invention, the switching means 5 comprise at least two field effect transistors Q1 and Q2, the gates G of which Q1 and Q2 can be controlled simultaneously by a control logic circuit 6 connected to the contact C.

Each transistor is connected between two diodes of the array by one of its outputs D.

The output D of transistor Q1 is thus connected between diodes D1 and D2 through resistor R4.

The output D of transistor Q2 is connected between diodes D2 and D3 through resistor R5.

The S gate of each transistor Q1 and Q2 is also connected to a common pole of the circuit connecting the flyer 2 and the anode (-) (contact B) of the capacitor 3.

Transistors Q1 and Q2 employ MOS technology. These components are inexpensive and easy to control by the programmable logic type circuit 6.

By controlling the transistors simultaneously, such a circuit may cause a continuous short circuit of three diodes, resulting in ignition of flyer 2.

The flyer 2 is initiated here by the avalanche of the diode, and therefore has a strong current to ensure initiation without placing the transistors Q1 and Q2 themselves in the avalanche.

The operation is as follows:

when controlling the two transistors Q1 and Q2, the first transistor Q1 connects the point between the two diodes D1 and D2 to the common pole B (0 volts). As a result, the diode D1 receives a reverse voltage equal to the charging voltage of the capacitor 3. This voltage can vary between 800 and 1450 volts and is in all cases higher than the reverse voltage of diode D1, which is 600 volts.

Diode D1 is then shorted (avalanche effect).

Furthermore, the switch of the second transistor Q2 has connected the point separating the diodes D2 and D3 to a common pole (0 volts). Since diode D1 is shorted, it is diode D2 that now receives the charging voltage of capacitor 3. The second diode D2 is then also shorted, and finally the diode D3 is subjected to the charging voltage of the capacitor 3, and then the diode D3 is shorted again, so that the input of the flyer 2 is directly connected to the positive pole (+) of the capacitor 3, the other input of the flyer being connected to the common pole B of the circuit 1.

A continuous avalanche of three diodes is thus obtained, detonating the flyer 2 for the charging voltage of the capacitor 3, which can vary between 800 and 1450 volts.

Resistors R4 and R5 are selected to be approximately 27 ohms. They can limit the current flowing in the transistor, in particular during avalanche. Therefore, all the energy contained in the capacitor 3 will indeed flow towards the flyer 2.

For example, a circuit having more than 3 diodes in series can of course be defined to realize diodes with lower reverse voltages. Other avalanche can then be controlled in association with other transistors. If N is the number of diodes Di used, the number of transistors Qi required is equal to N-1.

It can thus be seen that a device according to the invention can use static components with MOS technology without breaking the MOS by avalanche effect during low voltage (e.g. 800 v) initiation.

With the arrangement proposed by the present invention, a series of samples of the circuit can be subjected to a statistical destructive test (Neyer test) to determine the optimum voltage, thereby ensuring that other circuits of the same series operate with a given confidence and reliability.

Even if the required voltage is low, the avalanche effect will be ensured by the diode arrangement.

In this way, a compact and inexpensive ignition control circuit can be manufactured, and a desired level of reliability can be achieved.

Claims

1. An ignition control circuit (1) for an exploding foil pyrotechnic assembly (2), comprising at least one capacitor (3) which can be discharged in said pyrotechnic assembly (2) to detonate it, and a switching device (5) ensuring that the capacitor (3) in said pyrotechnic assembly (2) discharges, characterized in that said capacitor (3) is connected to said pyrotechnic assembly by an array of at least three diodes (D1, D2, D3), wherein at least three diodes (D1, D2, D3) are connected in series and in a direction preventing discharge of said capacitor (3), the sum of the reverse voltages of these diodes being greater than the maximum voltage which can be provided by said capacitor (3), said switching device (5) comprising at least two field effect transistors (Q1, Q2), the gates of which can be controlled simultaneously and are associated with an array of said at least three diodes (D1, D2, D3), and the ignition of at least two field effect transistors (Q1, Q2) being connected between each of said at least three diodes (D1, D2, D3) by the output of each of which said at least two field effect transistors (Q1, Q2, D2) is controlled in a short circuit.

2. An ignition control circuit according to claim 1, characterized in that each diode (D1, D2, D3) is associated with a parallel connected resistor (R1, R2, R3) and that the resistor (R1, R2, R3) makes it possible to limit and set the reverse voltage to which each diode is subjected.

3. An ignition control circuit according to claim 2, characterized in that each of at least two field effect transistors (Q1, Q2) is connected between two diodes via a resistor (R4, R5) such that the current flowing in the at least two field effect transistors can be limited.

4. An ignition control circuit according to any one of claims 1 to 3, wherein the at least two field effect transistors are MOS transistors.